High-speed production printers typically include a print controller that includes a print data path from a job storage system that spools print jobs to one or more print engines (also referred to as an “imaging engine” or as a “marking engine”). The print data path includes several components that process the print jobs to prepare pages for printing. Examples of components include a segmenter to segment a print job into pages, a layout master to create sheetsides, a rasterizer to rasterize the sheetsides into bitmaps, and a mechanism module to dispatch the sheet bitmaps (i.e., front and/or back sheetsides) to a print engine that physically marks paper using the sheetside bitmaps.
The components along the print data path may have queues to temporarily store data in memory for performing its job processing functions. As processing operations are completed, the data is forwarded down the print data path to the next component and queue, and the queues are continually depleted and refreshed in this manner as print jobs are processed in the print controller. To maintain printing at a high-speed, the print controller keeps the print data path sufficiently full with data such that the last queue feeding the print engine is able to continually feed the print engine with sheets at a fast rate. If the queue feeding the print engine runs empty, a condition known as a “back hitch” may occur in which the print engines stop printing and/or unintended blank pages fill the paper path and exit the printer.
In current print systems, when a user designates a print job as having a high priority (e.g., to print it soon at the expense of other previously submitted print jobs in various stages of processing in the print controller), it is necessary to clear the queues of the print data path to make room for processing the high priority print job. As such, when a high priority print job is detected, the print data path is immediately cleared to make way for the high priority print job. However, immediately cancelling a print job and clearing its data from the print data path means that the queues are emptied. Therefore, scheduling a high priority print job in current high-speed print systems often means creating a back hitch condition and wasting a significant amount of paper.